Boy are we off the opening post. But since it's been raised.
ATF Form 4473 17 nov 2017 (the latest 6 page version)
"Question 11 e. Are you an unlawful user of, or addicted to, marijuana or any depressant, stimulant, narcotic, or any other controlled substance? Warning: The use or possession of marijuana remains unlawful under Federal law regardless of whether it has been legalized or decriminalized for medical or recreational purposes in the state where you reside."
Search "legal definition "addiction" USA" returns the National Institute of Health definition:
"Addiction is defined as a chronic, relapsing brain disease that is characterized by compulsive drug seeking and use, despite harmful consequences. It is considered a brain disease because drugs change the brain; they change its structure and how it works."
Also, search "legal definition controlled substance USA" returns:
"Generally, a controlled substance is an illegal drug that can have a detrimental effect on a person's health and welfare. As a result, state and federal governments have seen fit to regulate these substances. ... To determine if a particular drug is legal, you should refer to the federal controlled substance schedules.
"What Is a Controlled Substance? - Criminal Law - FindLaw
"criminal.findlaw.com/criminal-charges/what-is-a-controlled-substance.html"
My bedside shotgun with 19" barrel is to me a short barreled shotgun, but under federal law it is not a Short Barrel Shotgun under Title II (1934 NFA).
Similarly, alcohol and tobacco may be taxed and regulated, but they are not federal Controlled Substances.
Controlled Suibstances Act:
"The term "controlled substance" means a drug or other substance, or immediate precursor, included in schedule I, II, III, IV, or V of part B of this subchapter. The term does not include distilled spirits, wine, malt beverages, or tobacco, as those terms are defined or used in subtitle E of the Internal Revenue Code of 1986."—21 U.S.C. § 802(6)